The invention is based on a method and apparatus for controlling at least one throttle cross section in a control line. Such apparatuses are already known (German Offenlegungsschriften Nos. 28 12 1292, 30 01 471, and 30 19 167), which however have the disadvantage that should the supply of electric current to the control motor fail or, if the apparatus is used in a motor vehicle, upon the shutoff of the internal combustion engine, the throttle device controlling the cross section of the control line will remain stuck in the open position as previously directed by the control motor, or else the throttle device is displaced into a completely closed or completely opened position, which can cause problems either in starting or during continued operation of the engine. An apparatus has therefore already been proposed, in which, upon the interruption of the supply of electric current to the control motor, the throttle device is movable by means of a spring element into a predetermined position which opens the throttle cross section of the control line.
However, such an apparatus requires very precise adjustment of the spring element, and there is an inherent danger that during continuous operation, changes in the fastening of the spring element or in the tension of the spring element itself may cause an undesirable change in the position of the throttle device while the control motor is in the non-excited state.